ruby-on-rails - ruby rails : Running custom validation function only when other properties are present

Question

我希望我的自定义验证器仅在它使用的属性存在时运行。

# these are all dates
validates :start_time, presence: true
validates :end_time, presence: true
validates :deadline_visitor, presence: true
validates :deadline_host, presence: true

# these validate the above dates
validate :validate_all_dates
validate :validate_dates

例子:

def validate_all_dates
  if self.start_time > self.end_time
    errors.add(:start_time, 'must be before or the same day as end time')
  end
end

失败，因为 self.start_time 和 self.end_time 不存在

Answer 1

你可以在validate方法中添加一个if参数，这样可以检查需要的条件。该参数可以是一个过程:

validates :validate_all_dates, if: Proc.new { |model| model.start_time.presence }

或者用一个方法:

validate :validate_all_dates, if: :dates_present?

def dates_present?
  start_time.presence && end_time.presence
end

查看本指南了解更多详情:Conditional Validation